1. Field of the Invention
Embodiments of the invention generally relate to computer database systems. More particularly, the invention relates to techniques for finding anomalous values for fields with temporal autocorrelation.
2. Description of the Related Art
Databases are well known systems for storing, searching, and retrieving information stored in a computer. The most prevalent type of database used today is the relational database, which stores data using a set of tables that may be reorganized and accessed in a number of different ways. Users access information in relational databases using a relational database management system (DBMS).
Each table in a relational database includes a set of one or more columns. Each column typically specifies a name and a data type (e.g., integer, float, string, etc), and may be used to store a common element of data. For example, in a table storing data about patients treated at a hospital, each patient might be referenced using a patient identification number stored in a “patient ID” column. Reading across the rows of such a table would provide data about a particular patient. Tables that share at least one attribute in common are said to be “related.” Further, tables without a common attribute may be related through other tables that do share common attributes. A path between two tables is often referred to as a “join,” and columns from tables related through a join may be combined to from a new table returned as a set of query results.
Queries of a relational database may specify which columns to retrieve data from, how to join the columns together, and conditions (predicates) that must be satisfied for a particular data item to be included in a query result table. Current relational databases require that queries be composed in complex query languages. Today, the most widely used query language is Structured Query Language (SQL). However, other query languages are also used. An SQL query is composed from one or more clauses set off by a keyword. Well-known SQL keywords include the SELECT, WHERE, FROM, HAVING, ORDER BY, and GROUP BY keywords. Composing a proper SQL query requires that a user understand both the structure and content of the relational database as well as the complex syntax of the SQL query language (or other query language).
The complexity of constructing an SQL statement, however, generally makes it difficult for average users to compose queries of a relational database. In medical research, there are often times when a user would like to analyze changes in data values over a certain time window. The researcher may wish to find data that can be classified as having a “temporal autocorrelation” characteristic, that is, if two measurements of a value occur close in time, then the values of those measurements are often very similar.